If you look at it dispassionately, it would seem that a lot of colleages would be rightly worried about this happening.

Why would we continue to renew H-1B visas if citizens need those jobs?

I doubt the Govt would legislate anything unless there is a sustained multi-year depression. They won't be able to react with new laws in a short time (at least under Biden and democratic congress). Whether companies will opt to hire H-1Bs or citizens is likely a cost decision. Existing employed H-1B renewals is totally dependent on company/individual performance.